Schaeffler North America

Variable valve train systems

Switching pivot element

Switching pivot elements allow switching between full lift and zero lift (valve or cylinder deactivation) in engines with an overhead camshaft. As a result, the thermodynamic efficiency of the engine can be optimised as a function of the engine load.

The switching pivot element consists of two nested housings, the inner and outer housing. The outer housing is rigidly positioned in the cylinder head. The inner housing is pressed against the end stop on the outer housing by a lost motion spring. Both housing parts can be linked by means of a coupling mechanism. The locking mechanism can be activated by hydraulic or electromagnetic means.

As in a standard pivot element, valve lash adjustment can be by hydraulic or mechanical means.

Modifications compared to standard valve train

  • Actuator integrated in oil circuit
  • Anti-rotation device in pivot element guide
  • ECU with data map for controlling actuator